Three-component organometallic-transition metal halide catalysts and olefin polymerization therewith



United States Patent THREE-COMPONENT ORGANOMETALLIC-TRAN SITION METAL HALIDE CATALYSTS AND OLE- FIN POLYMERIZATION THEREWITH Harry W. Coover, Jr., and Frederick B. Joyner, Kingsport, Tenn., assignors to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey No Drawing. Filed Mar. '31, 1958, Ser. No. 724,902

14 Claims. (Cl. 26093.7)

This invention relates to a new and improved polymerization process and is particularly concerned with the use of a novel catalyst combination for preparing high molecular weight solid polyolefins, such as polypropylene, of high density and crystalinity. In a particular aspect the invention is concerned with the preparation of polypropylene and higher polyolefins having a high crystallinity and a high density using a particular catalyst combination which has unexpectedly improved catalytic activity.

Polyethylene has heretofore been prepared by high pressure processes to give relatively flexible polymers having a rather high degree of chain branching and a density considerably lower than the theoretical density. 7 Thus, pressures of the order of 500 atmospheres or more and usually of the order of 1000-1500 atmospheres are commonly employed. It has been found that more dense polyethylenes can be produced by certain catalyst combinations to give polymers which have very little chain branching and a high degree of crystallinity. The exact reason why certain catalyst combinations give these highly dense and highly crystalline polymers is not readily understood. Furthermore, the activity of the catalysts ordinarily depends upon certain specific catalyst combinations, and the results are ordinarily highly unpredictable, since relatively minor changes in the catalyst combination often lead to liquid polymers rather than the desired solid polymers.

Certain metal derivatives have been suggested for use in conjunction with inorganic halides to produce high molecular weight polyethylene. Thus, it has been suggested that alkyl derivatives of alkali metals, zinc or magnesium can be used with transition metal halides in the low pressure polymerization of ethylene. When these catalysts are employed to polymerize propylene and higher a-monoolefins, the resulting polymeric product contains large amounts of oils, greases and rubbery polymers instead of the desired high molecular weight, crystalline product. Obviously, such results are unsatisfactory when a crystalline polymer is the desired product, and it is one of the purposes of this invention to overcome the undesirable results obtained when prior art catalysts are used.

This invention is concerned with and has for an object the provision of improved processes whereby m-IHOHO' olefins and particularly propylene can be readily polymerized by catalytic means to give high molecular weight, highly crystalline polymers. A particular object of the invention is to provide an improved catalyst combination which has unexpectedly improved catalytic activity for the polymerization of propylene and higher a-monoolefins to form crystalline high density polymers. Other objects will be apparent from the description and claims which follow.

The above and other objects are attained by means of this invention, wherein a-monoolefins, either singlyor in admixture, are readily polymerized to high molecula weight solid polymers by eifecting the polymerization in the presence of a catalytic mixture containing a metal derivative having one of the formulas RM, R M and RM X wherein M is an alkali metal selected from the group consisting of sodium, potassium and lithium and M is a metal selected from the group consisting of magnesium and zinc. R is a radical selected from the group consisting of alkyl radicals containing 1-8 carbon atoms, phenyl and benzyl and X is a halogen selected from the group consisting of chlorine, bromide and iodine. The second component of the catalyst is a halide of a metal selected from the group consisting of titanium, vanadium, zirconium, chromium and molybdenum, the halogen atoms being selected from the group consisting of chlorine, bromine and iodine, and the third component of the catalyst is selected from the group consisting of compounds having the formulas:

wherein each Y is an alkylamino (NR or alkoxy (-OR), said R being an alkyl radical containing 1 to 8 carbon atoms, and wherein n is an integer of 1 to 4. The improved catalytic activity of this mixture was wholly unexpected, particularly since mixtures containing only the organometallic compounds and the metal halides described above produce large amounts of comparatively low molecular weight products in the polymerization of propylene and higher olefins. The inventive process can be carried out in liquid phase in an inert organic liquid and preferably an inert liquid hydrocarbon vehicle, but excellent results can be obtained without using a solvent. The process proceeds with excellent results over a temperature range of from 0 C. to 250 C. but temperatures outside this range can be used if desired. Likewise, the reaction pressures may be varied widely from about atmospheric pressure to very high pressures of the order of 20,000 p.s.i. or higher. A particular advantage of the invention is that pressures of the order of 30-1000 p.s.i. give excellent .results, and it is not necessary to employ the extremely high pressures op um prnbq aql 'oxogo aieq Anassoosu 919M qorqm employed is desirably one which serves as an inert liquid ration of highly crystalline polypropylene, the polybutenes reaction medium.

The invention is of particular importance in the prepaand polystyrene although it can be used for polymerizing mixtures of ethylene and propylene as well as other amonoolefins containing up to 10 carbon atoms. The polypropylene produced in accordance with this invention is a highly crystalline polymer that can be used in molding operations to form products of excellent clarity. The high molecular weight, high density polymers of this invention are insoluble in solvents at ordinary temperatures but they are soluble in such solvents as xylene, toluene or tetralin at elevated temperatures. These solubility characteristics make it possible to carry out the polymerization process under conditions wherein the polymer formed is soluble in the reaction medium during the polymerization and can be precipitated therefrom by lowering the temperature of the resulting mixture.

The novel catalysts described above are particularly useful for polymerizing propylene to form a crystalline, high-density polymer. The polypropylene produced has a softening point above C. and a density of 0.91 and higher. Usually the density of the polypropylene is of the order of 0.91 and 0.92.

The polypropylene, polystyrene, polybutenes and other polyolefins prepared in accordance with the invention can be molded or extruded and can be used to form plates, sheets, films, or a variety of molded objects which exhibit a higher degree of stiffness than do the corresponding high pressure polyolefins. The products can be extruded in the form of pipe or tubing of excellent rigidity and can be injection molded into a great variety of articles. The polymers can also be cold drawn into ribbons, bands, fibers or filaments of high elasticity and rigidity. Fibers of high strength can be spun from the molten polymers obtained according to this process.

As has been indicated above the improved results ob tained in accordance with this invention depend upon the particular catalyst combination. Thus, one of the components of the catalyst is an organometallic compound having the formulas RM, R M and RM X wherein M is an alkali metal selected from the group consisting of sodium," potassium and lithium, M is a metal selected from the group consisting of magnesium and zinc, R is a radical selected from the group consisting of alkyl radicals containing 1-8 carbon atoms, phenyl and benzyl, and X is a halogen selected from the group consisting of chlorine, bromine and iodine. Another component of the catalyst composition is a halide of a transition metal selected from the group consisting of titanium, vanadium, zirconium, chromium and molybdenum, the halogen atoms being selected from the group consisting of chlorine, bromine and iodine. The transition metal can be at its maximum valency or at a reduced valency. Thus, titanium tetrachloride as well as titanium trichloride and titanium dichloride can be used in the catalyst composition. The third component of the catalyst composition is a compound having the formula:

Each Y represents a lower alkylamino or lower alkoxy radical, R is a lower alkyl radical containing 1 to 8, preferably 1 to 4, carbon atoms and n is an integer of 1 to 4. Among the specific compounds that can be used are tn's-N,N-dimethyl phosphor-amide, triethyl phosphate, mixed phosphate ester-amides, triethyl phosphite, N,N- dimethylacetamide, adipamide and the like.

The limiting factor in the temperature of the process appears to be the decomposition temperature of the catalyst. Ordinarily temperatures from 50 C. to 150 C. are employed, although temperatures as low as C. can be employed if desired. Usually, it is not desirable or economical to effect the polymerization at temperatures below 0 C., and the process can be readily controlled at room temperature or higher which is an advantage from the standpoint of commercial processing. The pressure employed is usually only sufficient to maintain reaction mixture in liquid form during the polymerization, although higher pressures can be used if desired. The pressure is ordinarily achieved by pressuring the system with the monomer whereby additional monomer dissolves in the reaction vehicle as the polymerization progresses.

The polymerization embodying the invention can be carried out batchwise or in a continuous flowing stream process. The continuous processes are preferred for economic reasons, and particularly good results are obtained using continuous processes wherein a polymerization mix ture of constant composition is continuously and progressively introduced into the polymerization zone and the mixture resulting from the polymerization is continuously and progressively withdrawn from the polymerization zone at an equivalent rate, whereby the relative concentration of the various components in the polymerization zone remains substantially unchanged during the process. This results in formation of polymers of extremely uniform molecular weight distribution over a relatively narrow range. Such uniform polymers possess distinct advantages since they do not contain any substantial amount of the low molecular weight or high molecular weight formations which are ordinarily found in polymers prepared by batch reactions.

In the continuous flowing stream process, the temperature is desirably maintained at a substantially constant value within the preferred range in order to achieve the highest degree of uniformity. Since it is desirable to employ a solution of the monomer of relatively high concentration, the process is desirably effected under a pressure of from 30 to 1000 p.s.i. obtained by pressuring thesystem with the monomer being polymerized. The amount of vehicle employed can be varied over rather wide limits with relation to the monomer and catalyst mixture. Best results are obtained using a concentration of catalyst of from about 0.1% to about 2% by weight based on the weight of the vehicle. The concentration of the monomer in the vehicle will vary rather widely depending upon the reaction conditions and will usually range from about 2 to 50% by weight. For a solution process it is preferred to use a concentration from about 2 to about 10% by weight based on the weight of the vehicle, and for a slurry type of process higher concentrations, for example up to 40% and higher are preferred. Higher concentrations of monomer ordinarily increase the rate of polymerization, but concentrations having 5-10% by weight in a solution process are ordinarily less desirable because the polymer dissolved in the reaction medium results in a very viscous solution.

The molar ratio of organometallic compound to transition metal halide can be varied within the range of 1:05 to 1:2, and the molar ratio of transition metal halide to the third component of the catalytic mixture can be varied within the range to 1:1 of 1:01, but it will be understood that higher and lower molar ratios are within the scope of this invention. A particularly eifective catalyst contains one mole of transition metal trihalide and 0.25 mole of the third component per mole of organometallic compound. The polymerization time can be varied as desired and will usually be of the order of from 30 minutes to several hours in batch processes. Contact times of from 1 to 4 hours are commonly employed in autoclave type reactions. When a continuous process is employed, the contact time in the polymerization zone can also be regulated as desired, and in some cases it is not necessary to employ reaction or contact times much beyond one-half to one hour since a cyclic system can be employed by precipitation of the polymer and return of the vehicle and unused catalyst to the charging zone wherein the catalyst can be replenished and additional monomer introduced.

The organic vehicle employed can be an aliphatic alkane or cycloalkane such as pentane, hexane, heptane or cyclohexane, or a hydrogenated aromatic compound such as tetrahydronaphthalene or decahydronaphthalene, or a high molecular weight liquid parafiin or mixture of paraflins which are liquid at the reaction temperature, or an aromatic hydrocarbon such as benzene, toluene, xylene, or the like, or a halogenated aromatic compound such as chlorobenzene, chloronaphthalene, or orthodichlorobenzene. The nature of the vehicle is subject to considerable variation, although the vehicle employed should be liquid under the conditions of reaction and relatively inert. The hydrocarbon liquids are desirably employed. Other solvents which can be used include ethyl benzene, isopropyl benzene, ethyl toluene, n-propyl benzene, diethyl benzenes, mono and dialkyl naphthalenes, n-pentane, n-octane, isooctane, methyl cyclohexane, tetralin, decalin, and any of the other well-known inert liquid hydrocarbons.

The polymerization ordinarily is accomplished by merely admixing the components of the polymerization mixture, and no additional heat is necessary unless it is desired to effect the polymerization at an elevated temperature in order to increase the solubility of polymeric product in the vehicle. When the highly uniform polymers are desired employing the continuous process wherein the relative proportions of the various components areimaintained substantially constant, the temperature is desirably controlled withina relatively narrow range.

. i This is readily accomplished since the solvent vehicle forms a high percentage of the polymerization mixture and hence can be heated or cooled to maintain the temperature as desired. The importance of the various components of this reaction mixture is evident from the fact that in polymerizing propylene a mixture of organornetallic compound and transition metal halide produces large amounts of low molecular weight rubbery polymer. However, when the third component within the scope of this invention is added to the mixture the resulting catalyst composition is highly efiective for polymerizing propylene to form a highly crystalline high-density polymer.

The invention is illustrated by the following examples of certain preferred embodiments thereof.

Example 1 This example illustrates the relatively large quantity of rubbery polymer obtained with a two-component alkali metal alkyl-transition metal compound. In a nitrogen-filled dry box a 1 g. catalyst charge comprising equimolar quantities of amyl sodium and titanium tetrachloride was added to a 500 ml. pressure bottle along with 100 ml. of dry heptane. The pressure bottle was then capped, removed from the dry box, and attached to a propylene source provided by means of a Paar hydrogenation apparatus. The mixture was agitated, heated to 70 C. and maintained under 30 p.s.i. propylene pressure for six hours. At the end of this period the resulting polymer was washed several times with dry methanol and then with water. The Weight of the polypropylene was 14.1 g. having a density of 0.898 and an inherent viscosity of 2.13. After extraction of the rubbery polypropylene by the use of dibutyl ether at 70 C., residual highly crystalline polypropylene weighed 8.5 g., had a density of 0.918 and an inherent viscosity of 2.65.

When TiCl replaced TiCl under the above conditions, a slight increase in crystallinity of the product was noted. The 13.9 g. of polypropylene product had a density of 0.905 and an inherent viscosity of 2.41. After extraction with dibutyl ether, the residual highly crystalline polypropylene weighed 9.7 g. and had a 0.918 density and an inherent viscosity of 2.72.

Example 2 When the process of Example 1 is repeated using a l-gram catalyst charge having a 1:1:0.5 molar ratio of amyl sodium, titanium tetrachloride and tris-N,N-dimethyl phosphoramide, the yield of crystalline polymer is more than doubled and the density and inherent viscosity of the polymer are increased.

Example 3 This example illustrates the relatively large quantity of rubbery polymer obtained with a two component magnesium or zinc catalyst. In a nitrogen-filled dry box a 1 g. catalyst charge comprising equirnolar quantities of phenyl magnesium bromide and titanium trichloride was added to a 50()ml. pressure bottle along with a 100 ml. of dry heptane. The pressure bottle was then capped, removed from the dry box, and attached to a propylene source provided by means of a Paar hydrogenation apparatus. The mixture was agitated, heated to 70 C., and maintained under 30 p.s.i. propylene pressure for six hours. At the end of this period, the resulting polymer was washed several times with dry methanol and then with water. The weight of the polypropylene was 12.4 g. having a density of 0.895 and an inherent viscosity of 2.09. After extraction of the rubbery polypropylene by the use of dibutyl ether at 70 C., the residual highly crystalline polypropylene weighed 7.4 g., had a density of 0.919, and an inherent viscosity of 2.51.

When diethyl zinc was used in place of phenyl magnesium bromide in the above example, the yield of polypropylene was 15.5 g. having a density of 0.903 and an inherent viscosity of 2.18. After extraction with dibutyl ether, the residual highly crystalline polypropylene weighed 10.8 g. and had a 0.917 density and an inherent viscosity of 2.30.

Example 4 When the process of Example 3 is repeated using a 1- gram catalyst charge having a 1:1:0.5 molar ratio of diethyl zinc, titanium trichloride and tris-N,N'dimethyl phosphoramide, the yieldof crystalline polymer is more than doubled and the density and inherent viscosity of the polymer are increased.

Example 5 In a nitrogen-filled dry box, a dry 280-ml. stainless steel autoclave was loaded with a 1.5-gram catalyst charge comprising a 1:0.5:O.1 molar ratio of butyl lithium, vanadium trichloride and tris-N,N-dimethyl phosphoramide. The autoclave was capped, removed from the dry box, placed in a rocker, and attached to a propylene source. A ml. (51 grams) charge of propylene was added, the autoclave was rocked, heated to 55 C. and maintained there for four hours. The product was isolated by washing with dry methanol and then with water. A 37.2 gram yield of highly crystalline polypropylene having a density of 0.919 and an inherent viscosity of 2.05 was obtained.

The above run was repeated using triethyl phosphite, triethyl phosphate, dimethylformamide and adiparnide in place of the phosphoramide in the above catalyst.

Example 6 The process of Example 5 was used with a catalyst having a 111:0.25 molar ratio of diethyl magnesium, titanium trichloride and tris-N,N-dimethyl phosphoramide. A 43.2-gram yield of polypropylene was obtained having a density of 0.919 and an inherent viscosity of 2.55.

The above run was repeated using triethyl phosphate, triphenyl phosphite, diethylacetamide and adipamide in the catalyst in place of the phosphoramide.

When titanium trichloride in the above catalyst is replaced by zirconium tetrachloride, chromic chloride, or molybdenum pentachloride improved yields of polyproplyene are realized. Similarly highly crystalline polyolefins were also obtained by using l-butene, 1- pentene, 4-methyl-1-pentene, styrene, .allyl benzene, fluorostyrene and vinyl cyclohexane as monomers in place of propylene.

Thus, by means of this invention polyolefins such as polypropylene are readily produced using a catalyst combination that has been found to have unexpected activity for producing highly crystalline polymer in excellent yields. The polymers thus obtained can be extruded, mechanically milled, cast or molded as desired. The polymers can be used as blending agents with the relatively more flexible high pressure polyethylenes to give any desired combination of properties. The polymers can also be blended with antioxidants, stabilizers, plasticizers, fillers, pigments, and the like, or mixed with other polymeric materials, waxes and the like. In general, the polymers embodying this invention can be treated in similar manner to those obtained by other processes.

From the detailed disclosure of this invention it is quite apparent that in this polymerization procedure a novel catalyst, not suggested in prior art polymerization procedures, is employed. As a result of the use of this novel catalyst it is possible to produce polymeric hydrocarbons, particularly polypropylene, having properties not heretofore obtainable. For example, polypropylene prepared in the presence of catalyst combinations within the scope of this invention is substantially free of rubbery and oily polymers and thus it is not necessary to subject such polypropylene of this invention to extraction procedures in order to obtain a commercial product. Also polypropylene produced in accordance with this invention possesses unexpectedly high crystallinity, an unusually high softening point and outstanding thermal stability. Such polypropylene also has a very high stiffness as a result of the unexpectedly high crystallinity. The properties imparted to polypropylene prepared in accordance with this invention thus characterize and distinguish this polypropylene from polymers prepared by prior art polymerization procedures.

The novel catalysts defined above can be used to produce high molecular weight crystalline polymeric hydrocarbons. The molecular weight of the polymers can be varied over a wide range by introducing hydrogen to the polymerization reaction. Such hydrogen can be introduced separately or in admixture with the olefin monomer. The polymers produced in accordance with this invention can be separated from polymerization catalyst by suitable extraction procedures, for example by washing with water or lower aliphatic alcohols such as methanol.

The catalyst composition have been described above as being elfective primarily for the polymerization of u-monoolefins. These catalyst compositions can, however, be used for polymerizing other a-olefins, and it is not necessary to limit the process of the invention to monoolefins. Other u-olefins that can be used are butadiene, isoprene, 1,3-pentadiene and the like.

The diluents employed in practicing this invention can be advantageously purified prior to use in the polymerization reaction by contacting the diluent, for example in a distillation procedure or otherwise, with the polymerization catalyst to remove undesirable trace impurities. Also, prior to such purification of the diluent the catalyst can be contacted advantageously with polymerizable monoolefin.

Although the invention has been described in considerable detail with reference to certain preferred embodiments thereof, variations and modifications can be effected within the spirit and scope of this invention as described hereinabove and as defined in the appended claims.

We claim:

1. In the polymerization of ot-IIIOIIOOlfifiHlC hydrocarbons containing 3 to 8 carbon atoms to form solid crystalline polymer, the improvement which comprises catalyzing the polymerization with a catalytic mixture consisting essentially of an organometallic compound selected from the group consisting of compounds having the formulas RM, RM and RM X wherein M is an alkali metal selected from the group consisting of sodium, potassium and lithium, M is a metal selected from the group consising of magnesium and zinc, R is a radical selected from the group consisting of alkyl radicals containing 1 to 5 carbon atoms, phenyl and benzyl and X is a halogen selected from the group consisting of chlorine, bromine and iodine, a halide of a transition metal selected from the group consisting of titanium, zirconium, vanadium, chromium and molybdenum, the halogen atoms being selected from the group consisting of chlorine, bromine and iodine, and an organophosphorus compound selected from the group consisting of tri-lower alkyl phosphites, tri-lower alkyl phosphates and hexa-lower alkyl phosphoric triamides, the alkyl radicals in said organophosphorus compound containing 1 to 8 carbon atoms, the molar ratio of transition metal halide to organophosphorus compound being within the range of 1:1 to 1:0.1.

2. In the polymerization of propylene to form solid crystalline polymer, the improvement which comprises effecting the polymerization in the presence of a catalytic miXture consisting essentially of an alkali metal alkyl wherein the alkyl radicals contain 1 to 5 carbon atoms and the alkali metal is selected from the group consisting of sodium, potassium and lithium, a titanium halide wherein the halogen atoms are selected from the group consisting, of chlorine, bromine and iodine, and an organophosphorus compound selected from the group consistingof tri-lower alkyl phosphites, tri-lower alkyl phosphates and hexa-lower alkyl phosphoric triamides, the alkyl radicals in said organophosphorus compound containing 1 to 8 carbon atoms, the molar ratio of titanium halide to organophosphorus compound being within the range of 1:1 to 1:0.1.

3. In the polymerization of propylene to form solid crystalline polymer, the improvement which comprises effecting the polymerization in the presence of a catalytic mixture consisting essentially of a metal alkyl wherein the alkyl radicals contain 1 to 5 carbon atoms and the metal is selected from the group consisting of magnesium and zinc, a titanium halide wherein the halogen atoms are selected from the group consisting of chlorine, bromine and iodine, and an organophosphorus compound selected from the group consisting of tri-lower alkyl phosphites, tri-lower alkyl phosphates and hexa-lower alkyl phosphoric triamides, the alkyl radicals in said organophosphorus compound containing 1 to 8 carbon atoms, the molar ratio of titanium halide to organophosphorus compound being within the range of 1:1 to 120.1.

4. In the polymerization of propylene to form solid crystalline polymer, the improvement which comprises effecting the polymerization in liquid dispersion in an inert liquid hydrocarbon and in the presence of a catalytic mixture consisting essentially of amyl sodium, titanium trichloride and tris-N,N-dimethyl phosphoramide, the molar ratio of titanium trichloride to tris-N,N-dimet-hyl phosphoramide being within the range of 1:1 to 1:0.1.

5. In the polymerization of propylene to form solid crystalline polymer, the improvement which comprises efiecting the polymerization in liquid dispersion in an inert liquid hydrocarbon and in the presence of a catalytic mixture consisting essentially of phenyl magnesium bromide, titanium trichloride and tris-N,N-dimethyl phosphoramide, the molar ratio of titanium trichloride to tris- N,N-dimethyl phosphoramide being within the range of 1:1 to 1:0.1.

6. In the polymerization of propylene to form solid crystalline polymer, the improvement which comprises effecting the polymerization in liquid dispersion in an inert liquid hydrocarbon and in the presence of a catalytic mixture consisting essentially of diethyl zinc, titanium trichloride and tris-N,N-dimethyl phosphoramide, the molar ratio of titanium trichloride to tris-N,N-dimethyl phosphoramide being within the range of 1:1 to 1:0.1.

7. In the polymerization of propylene to form solid crystalline polymer, the improvement which comprises effecting the polymerization in liquid dispersion in an inert liquid hydrocarbon and in the presence of a catalytic mixture consisting essentially of butyl lithium, vanadium trichloride and tris-N,N-dimethyl phosphoramide, the molar ratio of vanadium trichloride to tris-NJJ-dimethyl phosphoramide being within the range of 1:1 to 1:0.1.

8. As a composition of matter, a polymerization catalyst consisting essentially of an organometallic compound selected from the group consisting of compounds having the formulas RM, RM and RM X wherein M is an alkali metal selected from the group consisting of sodium, potassium and lithium, M is a metal selected from the group consisting of alkyl radicals containing 1 to 5 carbon atoms, phenyl and benzyl and X is a halogen selected from the group consisting of chlorine, bromine and iodine, a halide of a transition metal selected from the group consisting of titanium, zirconium, vanadium, chromium and molybdenum, the halogen atoms being selected from the group consisting of chlorine, bromine and iodine, and an organophosphorus compound selected from the group consisting of tri-lower alkyl phosphites, tri-lower alkyl phosphates and hexa-lower alkyl phosphoric triamides, the alkyl radicals in said organophosphorus compound containing 1 to 8 carbon atoms, the molar ratio of transition metal halide to organophosphorus compound being within the range of 1:1 to 1:0.1.

9. As a composition of matter, a polymerization catalyst consisting essentially of an alkali metal alkyl wherein the alkyl radicals contain 1 to 5 carbon atoms and the alkali metal is selected from the group consisting of sodium, potassium and lithium, a titanium halide wherein the halogen atoms are selected from the group consisting of chlorine, bromine and iodine and an organophosphorus compound selected from the group consisting of *tri-lower alkyl phosphites, tri-lower alkyl phosphates and hexalower alkyl phosphoric triamides, the alkyl radicals in said organophosphorus compound containing 1 to 8 carbon atoms, the molar ratio of titanium halide to organophosphorus compound being within the range of 1:1 to 110.1.

10. As a composition of matter, a polymerization catalyst consisting essentially of a metal alkyl wherein the alkyl radicals contain 1 to 5 carbon atoms, the metal is selected from the group consisting of magnesium and zinc, a titanium halide wherein the halogen atoms are selected from the group consisting of chlorine, bromine and iodine and an organophosphorus compound selected from the group consisting of tri-lower alkyl phosphites, tri-lower alkyl phosphates and hexa-lower alkyl phosphoric triamides, the alkyl radicals in said organophosphorus compound containing 1 to 8 carbon atoms, the molar ratio of titanium halide to organophosphorus compound being within the range of 1:1 to 1:0.1.

11. As a composition of matter, a polymerization catalyst consisting essentially of amyl sodium, titanium trichloride and tris-N,N-dimethyl phosphoramide, the molar ratio of titanium trichloride to tris-N,N-dimethyl phosphoramide being within the range of 1:1 to 120.1.

12. As a composition of matter, a polymerization catalyst consisting essentially of phenyl magnesium bromide, titanium trichloride and tris-N,N-dimethyl phosphoramide, the molar ratio of titanium trichloride to tris-N,N- dimethyl phosphoramide being within the range of 1:1 to 120.1.

13. As a composition of matter, a polymerization catalyst consisting essentially of diethyl zinc, titanium trichloride and tris-N,N-dimethyl phosphoramide, the molar ratio of titanium trichloride to tris-N,N-dimethyl phosphoramide being within the range of 1:1 to 1:0.1.

14. As a composition of matter, a polymerization catalyst consisting essentially of butyl lithium, vanadium trichloride and tris-N,N-dimethyl phosphoramide, the molar ratio of vanadium trichloride to tris-N,N-dimethyl phosphoramide being within the range of 1:1 to 1:0.1.

References Cited in the file of this patent UNITED STATES PATENTS 2,271,189 Anderson et a1. Oct. 18, 1955 2,827,446 Breslow Mar. 18, 1958 2,832,759 Nowlin et al. Apr. 29, 1958 2,840,617 Shokal June 24, 1958 2,846,427 Findlay Aug. 5, 1958 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 2,958,688 I November l 1960 Harry W. Coover Jr et a1,

It is hereby certified that error appears in the printed specification of the above numbered'patent requiring correction and that the said Letters Patent should read as corrected below.

Column 2 line 43,, beginning with the iupside down printed matter strike out all to and including "polymerizing" in line 4L8, same column, and insert instead the following: which were necessary heretofore. The liquid vehicle employed is desirably one which serves as an inert liquid reaction medium) The invention is of particular importance in the preparation of highly crystalline polypropylene, the polybutenes and polystyrene although it can be used for polymerizing column a line 41 for "diethylacetamide" read dimethylacetamide column 7, line 22 'for "composition" read compositions Signed and sealed this 18th day of April 1961c.

SEA L) Attest:

ERNEST W, SWIDER DAVID L. LADD Attesting Officer Commissioner of Patents 

1. IN THE POLYMERIZATION OF A-MONOOLEFINIC HYDROCARBONS CONTAINING 3 TO 8 CARBON ATOMS TO FORM SOLID CRYSTALLINE POLYMER, THE IMPROVEMENT WHICH COMPRISES CATALYZING THE POLYMERIZATION WITH A CATALYTIC MIXTURE CONSISTING ESSENTIALLY OF AN ORGANOMETALLIC COMPOUND SELECTED FROM THE GROUP CONSISTING OF COMPOUNDS HAVING THE FORMULAS RM'', RM2 AND RM2X WHEREIN M'' IS AN ALKALI METAL SELECTED FROM THE GROUP CONSISTING OF SODIUM, POTASSIUM AND LITHIUM, M2 IS A METAL SELECTED FROM THE GROUP CONSISTING OF MAGNESIUM AND ZINC, R IS A RADICAL SELECTED FROM THE GROUP CONSISTING OF ALKYL RADICALS CONTAINING 1 TO 5 CARBON ATOMS, PHENYL AND BENZYL AND X IS A HALOGEN SELECTED FROM THE GROUP CONSISTING OF CHLORINE, BROMINE AND IODINE, A HALIDE OF A TRANSITION METAL SELECTED FROM THE GROUP CONSISTING OF TITANIUM, ZIROCONIUM, VANADIUM, CHROMIUM AND MOLYBDENUM, THE HALOGEN ATOMS BEING SELECTED FROM THE GROUP CONSISITNG OF CHLORINE, BROMINE AND IODINE, AND AN ORGANOPHOSPHROUS COMPOUND SELECTED FROM THE GROUP CONSISTING OF TRI-LOWER ALKYL PHOSPHITES, TRI-LOWER ALKYL PHOSHATES AND HEXA-LOWER ALKYL PHOSPHORIC TRIAMIDES, THE ALKYL RADICALS IN SAID ORGANOPHOSPHORUS COMPOUND CONTAINING 1 TO 8 CARBON ATOMS, THE MOLAR RATIO OF TRANSITION METAL HALIDE TO ORGANOPHOSPHROUS COMPOUND BEING WITHIN THE RANGE OF 1:1 TO 1:0.1. 